The present invention relates to a method and an arrangement for correcting an angle-measuring and/or distance-measuring sensor system.
Sensor systems designed to measure an angle when a rotating object of measurement is involved, or to measure a distance when a linearly moving object of measurement is involved are already known per se, with which the information to be obtained is represented by a pair of sinusoidal and cosinusoidal measurement signals. The information is usually represented by the amplitude and/or the phase of these measurement signals. The measurement signals often contain angle errors or phase errors, which result from manufacturing tolerances or other circuit-related details in the sensor system.
It is also known per se that sensor systems of this type are designed based on the principle of GMR (GMR=giant magneto resistance) in order to determine the angle of a magnetic field. GMR angular-position sensors of this type ideally output the following signals:xideal=A·cos(α)yideal=A·sin(α)where A=amplitude. These signals are subsequently used to unambiguously determine angle α to be measured. GMR angular-position sensors of this type contain systematic errors, however, and the outputs therefore deliver the following signals:x=A1·cos(α)+x0 y=A2·sin(α+δ)+y0 
Since the variable to be determined is angle α, values x0 and y0 are the offsets of the angular-position sensor. Signal amplitudes A1 and A2 are usually different, and the phase shift between variables x and y is not exactly 90°; after subtracting the offset and normalizing for the same amplitude, the phase shift has phase error δ.
Publication DE 101 54 153 A1, for example, makes known a method for the offset compensation of an angle-measuring and/or distance-measuring sensor system, with which the values for x0 and y0 are determined via measurement, but with which the conditions for amplitudes A1=A2 and phase error δ=0 must be met.
In addition, a method is made known in DE 100 34 733 A1, with which amplitudes A1 and A2, values x0 and y0 and phase error δ are calculated from the measurement data. This calculation process is highly complex, so time is critical when it is used as a compensation process. Since the underlying equations are nonlinear in the required parameters, a nonlinear regression must be carried out; iteration and approximation procedures are used, which makes it impossible to calculate the amount of computing time required. The convergence properties of the known methods are highly dependent on whether or not a suitable initial solution has been selected, however. If an unfavorable selection has been made, methods of this type can be disadvantageous.